package chapter21;

import java.util.ArrayList;
import java.util.concurrent.*;

class TaskWithResult implements Callable<String> {
	private int id;
	
	public TaskWithResult(int id) {
		this.id = id;
	}

	@Override
	public String call() throws Exception {
		return "result of TaskWithResult " + id;
	}
	
}
public class CallableDemo {
	public static void main(String[] args) {
		ExecutorService exec = Executors.newCachedThreadPool();
		ArrayList<Future<String>> results = new ArrayList<>();
		for(int i = 0; i < 10; i++)
			results.add(exec.submit(new TaskWithResult(i)));
		for(Future<String> fs: results) 
			// get() blocks until completion
			try {
				System.out.println(fs.get());
			} catch (Exception e) {
				System.out.println(e);
			} finally {
				exec.shutdown();
			}
		
	}
}
